Investigating the Structure‐Property Relationships at Grain Boundaries in MgO Using Bond‐Valence Pair Potentials and Multiple Scattering Analysis

We describe the use of bond–valence analysis to investigate the segregation of calcium atoms at an MgO [001] tilt grain boundary. For small deviations away from the equilibrium metal‐oxide bond length, the bond–valence parameter approximates well to a Born–Mayer‐type pair potential. Therefore, by starting with a structural model determined from an atomic resolution Z‐contrast image, compositional and cation valence state information obtained from electron energy loss spectroscopy (EELS) can be incorporated into a comprehensive model for the grain boundary. For the boundary under investigation here, it is found that specific sites for preferential segregation can be identified, resulting in 0.3–0.4 monolayers of calcium in the boundary plane.